Ceramic fiber insulating material has been found useful when woven in fibrous form into mats or blankets. Although the material had desirable insulation characteristics it was found early on to lack significant mechanical strength as well as having poor structural qualities. Also at more elevated temperatures, such as about 2000.degree. F. (1090.degree. C.) or higher, the fiber blankets exhibit shrinkage. To compensate for these drawbacks, it has been proposed to form groups of individual batts into prefabricated modules. Then, such as shown in U.S. Pat. No. 3,832,815, the modules could be comprised of a series of individual side-by-side batts arranged in parallel, which could be crimped together at the cold face in module formation. This permitted the hot face portion of the batt module to flare out, thereby helping to compensate for the heat-induced individual blanket shrinkage.
It was also proposed to fold blankets, such as in U-shaped configurations, and hold them by support members within the fold. In U.S. Pat. No. 3,952,470, suspension arms with pointed tabs engage the support. The pointed tabs are pushed through the blanket for affixing to outer support means. By jamming the blankets together, and then folding the pointed tabs down over the support means, a flaring effect is achieved such as mentioned hereinbefore, for compensating heat-induced blanket shrinkage.
It has also been proposed to crimp or pinch side-by-side ceramic fiber blankets at the cold-face in a manner essentially providing support for the blankets by the crimping. Thus, U.S. Pat. No. 3,990,203 suggests such a festure combined with other support means which can form, when clamped together, self-supporting wall panels. In another variation, compression assisted by stacking of blankets has been proposed. Thus, in U.S. Pat. No. 4,088,825 the ceramic fiber batts are stacked and then compressed on their cold-face, in a structure promoted for use in an electric furnace wall construction. In another alternative, fiber strips can be held together by tubes and then adhered to a base plate with refractory adhesive. Then, as shown in U.S. Pat. No. 4,318,259, the plates can be pulled together and held firmly in place in an effort to close the seams between adjacent plates.
Other techniques that have been recently employed include folding of blankets in various configurations and pressing them onto hooks to compress the blankets into insulation rolls. Such configuration has been disclosed in U.S. Pat. No. 4,336,086. Also blankets can be squeezed into and against one another such as in alternating and overlapping U-shaped mats, as shown in U.S. Pat. No. 4,411,621. Or fibrous strips can be stacked flat and compressibly held down by anchor members firmly affixed to a furnace wall, such as discussed in U.S. Pat. No. 4,222,337.
In various of these structures, the replacement of individual blankets, or of modules, is also a consideration. For example in U.S. Pat. No. 4,411,621 individual U-shaped mat units at the interior of the furnace lend themselves to ease of replacement. In U.S. Pat. No. 4,287,839 individual blocks comprising an insulating mat folded in corrugated manner are designed for ease of replacement. By use of special cold-face structural plate configurations, with suspension hooks used as attaching means, the individual insulating blocks can be replaced from outside the furnace. By means of differing elements individual panels can be interlocked to form a self-supporting structure. Such a structure, as discussed in the above-mentioned U.S. Pat. No. 3,990,203, has the added feature of providing a portable chamber lining.
It would however be desirable to provide for a wall structure providing great ease of blanket or batt replacement. It would also be desirable to combine this with compression of the blankets or batts. An added advantage would be most simplistic ease in replacing sections even during heat chamber operation. Such features would best be combined with shrinkage compensating compression on the blankets, that would automatically adjust as shrinkage is encountered at high temperatures, and even for operations involving a range of elevated temperatures.